I enjoy walking in all its forms, from a simple stroll in the woods to multi-day backpack excursions. Though by no means an extreme ultra-light enthusiast, from spring to fall my preference is to carry a pack weight (before food and water) of 12 lb (5.5 kg), more or less. In recent years, I've rapidly moved to a philosophy of "lighter is better," within the constraints of budget and common sense.

I have avoided quoting the full technical specs here. The chipset used is the 32-channel Cartesio by STMicroelectronics, I recommend the DeLorme website for full details. However, the following are likely to be of general interest.

Topo USA Version 7.0Companion software, installed from plastic case containing the program on DVD. Included is a certificate for the download of up to $40-worth of DeLorme's Aerial Data packets. Also present are the three DVDs of Topo 7.0 data, which may be loaded direct to the GPS memory card or internal memory.

The DeLorme Earthmate GPS PN-40

PackagingThe unit was received well packaged and in sound condition. The GPS receiver, manual, software and two AA batteries were housed in an attractively printed box, which lists many of the features (both basic and technical) of the GPS unit and the software. The unit was much as expected from the web literature on the DeLorme site.

Warranty
As with most such devices, the DeLorme warranty is a bit more limited than that for most outdoors gear, although in line with warranties for consumer electronics. If desired, the warranty can be examined in full on the website (or in the manual), but the gist is summed up in the first two paragraphs:

"DeLorme warrants that your Earthmate GPS PN-40 will be free from defects in materials and workmanship for 1 year from the date of purchase. If your Earthmate GPS PN-40 fails in normal use, DeLorme will, at its sole option, either repair or replace the unit. DeLorme reserves the right to either repair or replace the unit with a new or refurbished unit at its sole discretion..." The manual goes on (p.82) to specify how to obtain a Return Material Authorization (RMA) from DeLorme.

Initial ImpressionsI have used the predecessor to the PN-40, the PN-20, for about two years, and a variety of other GPS units over the past ten. I already had Topo 7.0 installed on my system (but uninstalled and reinstalled from the DVD included). I have also used a variety of other mapping products over the years. I mention this because my perceptions of the product will unavoidably be those of a fairly experienced user of both GPS and basic mapping software.On receiving the PN-40 and installing the Topo 7.0 software, my first step was to visit the DeLorme forum website, as often firmware updates are available in beta form before being distributed (normal distribution is handled via the Topo 7.0 software). I downloaded and installed (without problem) the present 2.5 firmware public beta, having checked the comments on the forum to see if there were any seriously adverse comments (there were not). The DeLorme forum, I should mention, has always proven an admirable source for support, although for significant issues the necessary procedure is to contact the firm direct.

The PN-40 is easy for me to operate, as the controls are identical in appearance (and, in large part, functionality) to those of the PN-20. They are well labelled and intuitive. In part this is because of the way the firmware (the operating system for the unit) is designed. The functions that are needed to operate the unit properly are rarely buried below many tiers of menus. The controls have a pleasing crispness to their operation. A button-press is accompanied by a gentle click, which provides useful auditory feedback. I have already used the unit wearing gloves, and with a reasonably light pair found no problems The clarity and resolution of the screen display is excellent, as is the brightness, which is fully controllable, another key factor in ease of use. There is, however, no mechanism for the change of screen contrast.

I had the batteries loaded and my first GPS location fix within a half-hour of having unpacked the unit. I have since used it in the field, on a particularly demanding backcountry traverse. When stationary the acquisition of satellite signals is quite fast (even when the unit is turned on at a new location). I did find that when moving, even with a clear open sky, initial satellite acquisition while walking could take some minutes. It seems very much faster to wait, stationary, for a satellite lock than to attempt to achieve one while ambulatory. Indeed, so slow was acquisition in this case that I was convinced that the unit might be faulty, but subsequent testing has showed such a high speed of satellite acquisition when standing still that I am now convinced that this is a peculiarity of the unit, for which I will accommodate.

The PN-40 has an internal compass and barometer (these can be activated and deactivated from the main device control menu). The compass is reliant on an internal accelerometer, and the compass must be calibrated before use (true also for the barometer). The accelerometer operates on three axes, and a series of three movements must be used to calibrate, a procedure that DeLorme informally calls "the dance." I have had indifferent success with this, having obtained calibration perhaps one time in five. Even after calibration, the compass seems to have a will of its own. I am not yet sure if this is potentially a defect (if so, it is likely with the accelerometer), but I am considering returning the unit to DeLorme to have this checked out, and have even obtained an RMA. However, I want to get a little better sense of this aspect of the unit before doing so, in case the problem is my operation of the GPS. Since the compass, while a very useful feature, is not critical to operation, in my opinion, I am filing this initial report, and will report on my decision in the Field Report.

Quality of instructionsAs with any piece of electronic apparatus, the manual is key to understanding how to operate a GPS. The PN-40 manual is quite well-written and comprehensive. There's a useful "Getting Started" section, with the basics of battery installation and turning the unit on for the first time. The functions of the buttons are described here. There is, rather surprisingly, no diagram of the front and back of the case, but as the buttons on the unit are generally labeled or otherwise obvious, this may have been considered unnecessary. If I were a beginning user, I might consider this a shortcoming. A view of both front and back is shown in this report. Various other basics of operation are discussed in the manual's introduction.

After this, there's a section of "Scenarios." This is an excellent idea, in my belief. Before the details of the various unit functions, this shows how the GPS can be used in a variety real-world settings, including geocaching (both hiding and finding), birdwatching, mountain biking and (especially interesting) mapping assets in the field. This last is directed more to corporate use and presupposes the availability of DeLorme's XMap software. Clearly, the manufacturer is hoping that this GPS will see industrial use. These examples of how the GPS can enhance (or, in the case of geocaching, enable) these pursuits was, I found, very helpful. This was particularly the case with geocaching, which is an activity I rarely pursue. There is now a dedicated geocaching function in the PN-40's menus, and a free membership for thirty days to geocaching.com is offered with a coupon card contained in the unit's carton.

The balance of the manual describes the operation of the GPS on a screen-by-screen basis. Using a book metaphor, DeLorme terms the various operational screens "pages," pretty much standard terminology with GPS units. The margin of the text in this section of the manual provides screenshots as well as some helpful hints, highlighted in boxes. I found the manual useful in answering a number of questions. The only caveat that I have is that it isn't as well indexed as it might be. However, it may also be downloaded from the DeLorme website in PDF form, and it can then be completely searched on any word using Adobe Reader's search functions. I've saved that to my desktop. Indeed, this is advisable, as DeLorme issues updates to its manuals in this form, and these contain information not in the original manual. For example, the satellite page now shows yellow bars in addition to red, yellow, and green; this is documented only in the updated online version.

Customer Service
Because of some initial concerns, mostly mentioned above, I contacted DeLorme several times via email, and found response time fast, and answers helpful. I have not yet had occasion to contact the firm by voice about this unit.

Operation and Features

It's not really possible or appropriate to provide comprehensive instruction on the operation of this GPS in a review. For those who may want to get a sense of unit operation I recommend the PDF manual mentioned already. Still, I want to familiarize readers with the basics of operation of the PN-40, so I can intelligently discuss my experiences with the instrument. The controls of the unit, its buttons, pages and menus, are not that different from many models of GPS.

First, here's the front panel of the GPS, largely self explanatory.

To power the GPS on, the small red "Power" button is held down for a moment (the manual states for 1.5 seconds), and then released. The same button, if held down for seven seconds, will turn the unit off (in most cases) in the event of a "freeze." The DeLorme boot screen shows briefly, followed a few seconds later by the Satellites page. The GPS immediately starts to acquire satellite signals. Once on, if the "Power" button is held down for about 2 seconds, a slider bar appears, which enables the screen brightness to be altered. If the button is pressed briefly once while the unit's on, the "power down" screen shows. When the Enter key is pressed subsequently, the GPS will turn off. This two-button shutdown seems to me to be a good idea, as it prevents accidentally shutting the unit off.

Above are two views of the back of the GPS case. On the left, the back is shown held in place with two D-rings. These are attached to brass screws, and turning the rings clockwise fastens the back tightly. Once the back is screwed in place, the D-rings fold down flush and are retained in position by two small projecting plastic ribs. To install the AA batteries (or lithium-ion power pack) and the SD card, the back must be removed, to expose the battery compartment (image on right). To install the card, press on the small bar marked "PUSH." This releases the SD slot, which then swings up. The card slides into position, with the contacts going in first and facing the interior of the GPS (i.e. with the label on the card facing towards the user). The slot is then pushed down until it clicks into place. The batteries may then be installed (polarity as indicated in the diagram). The back is then replaced using the screws attached to the D-rings, which are folded then folded flush. The GPS is now ready for operation.

When I turned the GPS on for the first time at my home location, I was pleasantly surprised at how quickly the unit provided an accurate first "cold" fix. I had a solid location in around forty seconds, which is quite impressive.

This speedy start may have been an anomaly, but I have been consistently impressed, during my preliminary use of the PN-40, by the speed of signal acquisition. It's generally capable of getting a location swiftly even inside a building or in dense brush. As yet, there are no leaves on the trees, but based by the quality of satellite acquisition I am able to get within my house, I shall be surprised if the heavy woodland canopy of the spring and summer Catskills will cause any significant problems with reception.

GPS pages
In order to give a sense of what it's like to use this GPS, what follows are a list, with comments, of the main pages of the GPS, together with a description of their layout and function.

Satellite page

This is the screen seen after the GPS has fully booted. Unless the GPS location function is turned off from the Setup menu (this can also be done by using the Menu button directly from the Satellites page), the top section of this page shows a circular view of the sky with superimposed directions (North up), with approximate satellite positions set against a circular grid. Below this is a graph showing which satellites are available, and the signal strength and status of each. A blank means that the satellite is not yet being received. Red indicates that it is being tracked, but no data has yet been received. Green indicates that the satellite is being tracked, ephemeris data is being received (one of several data streams from the GPS satellites), and the satellite is being used for navigation. Yellow means much the same, but that predicted ephemeris data is being used.

Blue means much the same, but indicates that additionally the satellite being tracked is providing WAAS correction, a technology that enhances the accuracy of GPS position fixes. I have found that the mere fact that the WAAS satellite (marked as satellite 138 by the GPS, here on the East Coast) is shown as being tracked does not, apparently, mean that WAAS correction data is being received. According to DeLorme's manual, when WAAS correction is in operation, the letters "WAAS" show at the top right of the screen, something I have not often seen so far. When it works, almost all of the satellite strength bars in the chart turn blue. This is a worthwhile improvement for some purposes, but acquiring WAAS satellite data does cause a power drain. For general navigation I may not be justified in enabling WAAS all the time. The satellite page also shows the quality of fix (what DeLorme refers to as 2-D and 3-D, which depends on the number of satellites and the quality of data monitored). This screen also shows the estimated accuracy of fix, expressed as a tolerance: +/- [distance in feet or meters], the time, and the elevation.

The bottom of the screen has a bar that indicates battery strength. For this to be accurate, it's critical that the correct battery type is selected in the Setup page. If the wrong type is set, the battery life shown is highly misleading. For example, if the indicator is set to "lithium-ion battery" and a pair of standard alkaline AA cells are used, the battery life will be shown as almost exhausted from the outset.

Map page

This is the heart of the GPS, its reason for existence. The Map page has an extraordinary wealth of options, not all of which I am able to touch on here. All of the configuration is done via the Menu key, which provides access to three page-specific items: "Show info fields," "Measure distance," and "Map setup." The GPS has a pre-programmed world highway base map (I'm using DeLorme's designations for the various map types here). This is hardwired into the unit, and provides only the most basic data. Shown are major cities, coastal outlines, and main roads. For the US, only Interstates are labeled on the map, but the names of other main roads are displayed if the map cursor is "panned"moved using the arrow keysover the road, whereupon the road name is displayed at bottom left. This map is useful only for the most rudimentary kind of navigation, primarily city-to-city.

All remaining types of map data must be uploaded to the GPS (or, more accurately, to the internal memory or to the SD memory card, which is where such maps are stored). The speed of upload of map data is reasonable for removable media storage, which means that for very large map files, upload can be a somewhat slow process, but this limitation is largely inherent to the type of storage: writing to SD cards is not especially fast. However, they are cheap, and they have a conveniently small form factor.

I have moved about 480 MB of map data to the internal memory, using the appropriate screen in Topo USA. (That space is sufficient, incidentally, for the USGS quads for the entire Catskill region.) I have the DeLorme Street and Topographic maps for Pennsylvania, New Jersey, and New York (a substantial amount of map data) loaded onto a 2 GB SD data card, with plenty of room to spare. If I'm going to have maps and imagery for several such extensive areas, it's going to be most convenient to purchase a number of high-capacity SD cards (the unit will handle up to 32 GB), and swap these in and out as my travels dictate. Such cards are now cheap, at least in the lower memory sizes.

The software provided with the PN-40 offers two types of map that may be uploaded. These are regional routable maps (part of DeLorme's Street Atlas USA dataset, designed primarily for automobile navigation). They are handled from the three-DVD set, along with DeLorme Street & Topographic, a high-resolution contoured map, suitable for serious navigation. The remaining types of map data, prepared via Topo 7.0, are USGS 7.5-minute quads, DOQQ (USGS Digital Orthoimagery Quarter Quadrangles) aerial imagery, and satellite imagery ("Sat 10 data" i.e. with 10 m, 33 ft resolution). These last three types are available for a fee, and also require Topo USA for purchase and preparation. It is now possible for $29.95 to purchase an annual subscription to much of DeLorme's data, something I have now done. It's also possible to upload imagery prepared with DeLorme's XMap product, but I do not own this.

The ability to show USGS maps, let alone aerial and satellite imagery, is an exciting development in the development of GPS technology. I especially like it as I usually use USGS sheets for backcountry navigation, and it's handy to have the same map on the GPS as I have in my hand! Many GPS units that display maps provide rather basic offerings, at additional cost. While I rarely find aerial and satellite imagery especially useful for navigation (in my part of the world, the terrain is cloaked by trees, it is (at the very least) a nifty and intriguing feature.

Various information fields may be displayed on the map page, according to the type of navigation that's being done. What's displayed may be chosen by the user. I'll discuss this aspect, and my experiences with uploading and using all types of maps, in the Field and Long Term reports. The speed of screen redraws is very fast with the PN-40.

The map's orientation can be altered using the menu key. So far, I have generally selected "North up," much as I would use a paper map. Other options are "Heading up," with the top of the map oriented in the direction of the current bearing, and "Course up," used when navigating a route, with the finish point always at the top of the screen. Another other tool of interest, accessible through the Menu key, is the "Measure tool." This may be used to measure distances and areas on the GPS.

The direction of travel is indicated, as with most GPS units, by an arrow-like pointer displayed on the map. The PN-40 determines direction from the compass (at speeds below 1.5 mph, 2.4 kph), or from the GPS signal, at speeds over that. As previously noted, I have had some preliminary issues with the compass, and I cannot yet comment on the utility of this aspect of the instrument.

Other important menu items control which uploaded maps display, and in what order. These functions are found under "Map setup": the "Data Layering" and "Data management" tools. Suffice it to say that these are critical to the way that uploaded maps display, but beyond the scope of this review.

Compass page

This shows a graphic resembling a traditional compass. The exclamation mark in the box at lower right indicates that the bearing shown is not accurate; the electronic compass is not functional. If it were, the bearing shown on the screen (set by me to true north in the setup page) would be an accurate bearing.

Trip info page

This is a fully customizable page, whose data fields can easily be altered to suit whatever activity I'm engaged in. For example, on bicycle trips, I am curious to know my maximum and average speeds, statistics that I never measure for hiking. Therefore, I set the GPS (with the Menu button) to display those items.

For hiking and backpacking, I'm able to see sunset/sunrise (and moonset/moonrise), useful for obvious reasons, especially for backpacks. The same screen can simultaneously show position (UTM/UPS or latitude/longitude), elevation, maximum elevation etc., etc. Resetting the data is easily accomplished through the Menu button, and it's possible to reset some fields without resetting them all.

Find page
This may be reached via the Find button. There are a variety of categories of information, and two find options: "Find Near Map Center" and "Find By Name Contains." The first orders the list according to distance from the position indicated by the GPS. Available via Find are waypoints, points of interest, natural features, addresses, coordinates, cities, and streets/trails. This is a powerful tool. The extent to which it is enabled depends on the type of maps loaded into the unit (if USGS maps alone are present, this feature will not work). Options (as in most pages) are reached via the Menu button. The speed of find is very fast.

Waypoints Page
This can be reached by "leafing through" using the Page button, but is also quickly available via the Make Waypoint button. A wide selection of waypoint symbols (described in the manual) is available, and the waypoint can be labeled, deleted, and commented (using the "virtual keyboard" which is accessible when the cursor is in certain fields). I have created a variety of waypoints so far, including both summits and arbitrary points. The procedure is straightforward and the results accurate. A nice feature is the "Average Waypoint" on-screen button which takes a succession of position fixes at intervals of about one second for additional accuracy.

Routes page
This may be reached via the Setup key, or (if enabled in setup) by moving through pages via the Page key. It is customizable and controllable (e.g. to delete a route) via the menu key. It is possible to simulate navigation on a route (road or direct line) in this page. Using this page it is possible to calculate a driving route, although the usual caveats for such devices need to be observed. At least one local road shown on projected routes is no longer open for traffic.

Tracks page
I have used this page frequently in my early tests, and find it very straightforward. It is reached in the same manner as the Routes page. Generally, before creating a track, I use the Menu button to set the option that alters the recording interval settings. There are two types of interval, time and distance. I generally use time. Also programmable is the recording interval. The default is rather short (two feet or two seconds, as I recall), which may be useful for making a highly detailed map but seems overkill for recording the average trip. Also, since the track is limited to 10,000 points (position readings) it means that with such a low setting the track log (remaining capacity is shown by a percentage progression bar) will fill faster. With a two-second interval, the track log would fill in about 5.5 hours. By using a longer interval, tracking may be continued for a full day, or even several days, depending on the setting selected. Once a track is completed it may be saved (up to ten tracks may be stored on the machine) or discarded. If it is saved, the distance of the track is briefly displayed. Using the Follow (virtual) button converts the track to a route, which means that it can then be renavigated using the Route page. Saved tracks may be edited (for color etc.), hidden, viewed, converted to routes later, or discarded.

Sun/moon page

This gives the moon's phase, moonrise/moonset, sunrise/sunset and the position of the sun and moon in relation to a compass. Not a major page, but a very handy one!

Tide page

This provides tide information, both at the time to which the GPS is set and at a future or past time. It does so for a number of tide stations, sorted by proximity to the GPS. It does this for a variety of user-selectable locations. As I kayak both on the Hudson River (which is tidal) and at sea, this is a feature I like very much indeed.

Other Pages

Not mentioned so far are the Geocache page, which facilitates geocaching. I will be testing this in due course. There is also a Hunt/Fish pages, which suggests whether a particular day is good for these purposes, and provides the optimal times. I am unclear on what basis is does so, but will be unable to comment further on this as I don't hunt or fish.

Device Setup page

This last page is key to the operation of the GPS. From here, the system may be modified, by disabling the GPS function, setting the unit to power saving mode, controlling the onboard sound, etc. WAAS may be turned off and on (since it consumes some additional power to have WAAS enabled, it's a good idea to disable it in an area where WAAS corrections can't be received). Battery type is also set from here. Display, interface, sound, page order, time and units are all controlled from this page. The Units sub-page bears special mention, as this is used to set coordinate type (latitude/longitude in various forms, or UTM/UPS), the datum, whether the bearings shown are true or magnetic, whether ground measure is imperial, metric or nautical, etc. The range of available datums is impressive

I've attempted to summarize the operation of the GPS in this initial report, but with a tool so rich in features it's impossible to do more than just outline the wealth of available options. My main focus in the coming four months will be on how well they work.

GPS power use
I've already found that the backlighting of the GPS is sufficient to make the GPS easily read even in bright sunshine. There is also a mode for night use, and in fact the unit may be set so this is automatically turned on after dark (this is presumably determined by the unit's internal clock, and the sunrise-sunset ephemeris it contains). With the compass and barometer turned on, the alkaline batteries I have been using seem to be quickly depleted, and I will definitely need to carry a spare set. To some extent battery use can adjusted. The most effective method of doing so is to set the unit to "Power Saving" mode in the System screen of the Device Setup page. This sets the backlight to 10 percent intensity and sets the backlight time (the duration that the backlight is brightly on after a button press) to 15 seconds, the minimum period that may be specified. It does leave WAAS on, and as previously noted, this creates a small power drain, so this too may be turned off. If a trail is being created, setting the time (or distance) interval to a larger value may also cut down on power use, although this will also reduce the accuracy of the trail. This is a trade-off that needs some thought, depending on the intended use of the data. Clearly, for mapping, this would be unsatisfactory.

I have not yet used the unit with lithium AA batteries (an expensive option, but likely an an effective one in winter). From my initial use, I still don't have a really good sense of what period of usage may be expected from a set of standard alkaline AAs (beyond the fact that it seems shorter than ideal when all features are enabled), and I will report on this in due course. I will also experiment with rechargeable Lithium Ion batteries, as I have a suitable charger and a couple of appropriate CRV3 batteries, though I will probably get a new one for testing purposes as these no longer hold charge for as long as they did when new.

The GPS can be powered directly via the USB port (clearly, an option that useful in the field only if a small laptop is also carried). It will accept standard alkaline, lithium and NiMH cells, or a rechargeable lithium-ion battery pack. Whatever cell type is chosen, it needs to be specified in the "System" screen in order for the power meter to correctly estimate the rate of depletion.

The manual states that batteries should be removed from the unit when it is in storage. This procedure is suggested if I use the GPS intermittently (e.g., more than a month between uses).

Topo USA Version 7.0

This accompanying software is supplied with the GPS, and is optimized for use with the PN-40 and PN-20 GPS units. It is requisite for uploading USGS maps and similar imagery to the GPS, and for downloading data from the GPS to maps. However, its use for map upload could potentially be avoided if only the Topo USA 7.0 maps are used on the GPS. These can be loaded directly from a three-disk set (US East, Central, and West regions).

Topo USA 7.0 contains the tools for the purchase and download of additional map imagery, and has a host of powerful functions. The interface will be reasonably familiar to users of some DeLorme software. This is a relatively powerful and complex program, not a simple utility. It offers 3-D views of mapped terrain, the ability to views various types of map imagery. a wealth of features for routing, and a great deal more.

It does have abundant onboard help. Not only are there many hints associated with actions (these can be turned off if they become annoying) but the help button, in addition to giving access to a standard Windows-style help system, also brings up an extensive manual in PDF format.

The computer must be running Windows XP with Service Pack 3 installed and 128 MB minimum (256 recommended); or Windows Vista with at least 512 MB RAM. 1 GB of hard drive space should be available, along with a 3-D capable video card with 32 MB of VRAM. Previous versions of the software may be retained.

So far I have experienced occasional stability issues with the updated program, but not (so far) sufficient to impede its operation. I have used the program to "cut" and upload a series of USGS maps to the PN-40. This it has done smoothly and satisfactorily. I will report more on Topo USA 7.0 and its functionality in my field and long term reports, once (as I hope) I have a somewhat more stable installation.

Summary

Despite some initial teething pains, the Earthmate GPS PN-40 has impressed me so far as a solid piece of work. Having been a PN-20 user, I am glad to see many of the concerns I have with that GPS addressed. However, even if I came to the unit with no such background, it would be very hard for me not to like the availability of USGS maps, DOQQ, and satellite data; the integration with powerful software; and the host of features that the PN-40 contains. The positional accuracy, in circumstances where I have been able to gauge it against known locations on the USGS basemap, has generally been exceptional. The speed of signal acquisition (though this seems best done with the unit stationary) is speedy, and the number of satellites acquired numerous, very often a full constellation (though the WAAS satellites seem, as is common in most GPS units, much harder to lock in). This last issue is in part a function of my fairly northerly location, as the WAAS satellites are low in the sky at this latitude (they are in equatorial orbit). I am pleased to see that even with the internal barometric altimeter turned off, estimates of elevation are realistic and generally in line with the USGS basemap.

FIELD REPORT

FIELD LOCATIONS AND CONDITIONS

I have used the DeLorme PN-40 GPS over the past two months for one two-day backpack, a variety of day hikes, and several bicycle rides. Temperatures have ranged from 40 F (4 C) to 75 F (24 C). Use was in the Catskill and Shawanagunk Mountains of New York, to elevations of about 4000 ft (1220 m). Hiking weather conditions were generally mild, sun and light rain, over sometimes fairly rugged terrain.

PERFORMANCE IN THE FIELD

I returned the PN-40 to DeLorme shortly after posting the Initial Report, when it unexpectedly failed to boot. I received the same unit back within about a week of its receipt by Delorme (a good turnaround time, in my opinion) with a note that the "back plastics" had been replaced. My maps were still in the unit's internal storage (I had removed the SD card before shipping). I don't know what the "back plastics" that were replaced are, but the unit has worked well subsequently, with no repeat of the problem. I have also updated the unit's firmware once more, from the 2.5 public beta to the official release version of 2.5. This was very straightforward. It did cause the resetting of a few preferences in the unit's settings, but no major issues.

I have used the PN-40 with lithium batteries, rechargeable Li-ion batteries, and standard alkaline cells. This is the approximate order of battery life in the unit (for those battery types with which I have experimented). On hikes I usually use the setting (found under the Device Setup/GPS Settings menu) for extended battery life. This decreases the screen brightness; decreases the time the screen is on after pressing a key; and sets a fairly low frequency for recording position. One minor peculiarity I have noted is that the screen brightness does not reset to normal once the unit is reset to normal power use. I have to manually readjust it, by holding the power off button down for a number of settings and then using the slider control that pops up on screen. This isn't a serious issue, but worthy of comment.

I don't have a hard and fast lifetime for disposable lithium batteries in the unit yet, but I have determined that the life from one charge of a rechargeable Li-ion battery seems to be about twelve hours or a little more (that use was extended over two days). One caveat; the sound setting that informs me that the batteries are getting low is not very audible, to me at least. This resulted in total loss of power to the unit during the second day of my backpack.

Through what may be a peculiarity of the power discharge curve of the Li-ion battery, the PN-40 (which I was carrying in my pocket) seems to have stopped stone cold on the second day of my backpack. This, rather than a proper shutdown as (I am informed by the DeLorme forums) is supposed to occur when battery power runs very low. As a result, the track data was entirely lost for the second day of my backpack; this information was not saved. In addition, once I noted that the unit was oit of power (during a brief rest stop), and had put replacement batteries in, I had a great deal of of trouble, despite an excellent clear sky view, in getting the PN-40 to find its location. (I knew where I was; I wasn't using the GPS for primary navigation.) In fact, I eventually gave up, as I was then quite close to the end of the large loop of trails I was hiking. This was rather a disappointment from the aspect of performance, and I am hoping that there may be a firmware fix to this issue to come at some future point. Once I did achieve a location fix again (when back at home), the unit's ability to quickly establish its location was subsequently unimpaired.

For all that, given that the GPS was just stuck in a pants pocket, it kept a remarkable good track on the first day. Below is my first day's track, imported into Topo 7.0. Communication with the GPS on the computer is very straightforward. I just connected the supplied cable to the back of the GPS, and connected the other end to a USB port on my computer, and used the "Handheld Export" function (the tab for which is visible at bottom center of the image below) to import the track, then highlighted it and used the profile function to show my walking distance, terrain profile, etc. (see window at bottom of image).

I was travelling from north to south, from the trailhead to a charming spot called Long Pond. So far as I can tell, the recorded track is quite accurate; it shows (for example) my track round Long Pond quite well. In places, the track deviates significantly from the position that DeLorme indicates on its basemap as the location of the Mongaup-Hardenburgh trail, but this trail is infrequently travelled and has seen significant rerouting. I believe the GPS track is accurate. In addition (though this is difficult to see in the screen shot) the green line in the elevation profile that indicates the GPS unit's calculated elevation is generally a fairly close match for the map elevation. It's also possible to include hiking speed in the profile at the bottom of the screen. The Topo software is quite good, although I continue to find it a trifle unstable on my Windows XP machine, but not enough to be a serious nuisance. A new version (8.0) is out, and I am hoping to obtain it; perhaps it will resolve the stability issues. I should stress that the problem may be my machine's configuration, not the DeLorme software.

In the Initial Report, I had mentioned some issues with the movements necessary for compass calibration. This turned out to be my error. I hadn't followed the onscreen instructions quite right. Once I determined what I was doing wrong, I found that calibration is fast, easy, and provides accurate results (I have checked the GPS headings with a compass and they are pretty much spot on). DeLorme recommends that calibration is done when the battery is changed, but practically speaking I find it better to do this more often, as it seems that the quality of calibration changes when, for example, the battery voltage drops. Being able to see both my location and travelling direction on the map page is very handy.

I have downloaded map data from DeLorme, using the Topo 7.0 interface. I elected to obtain aerial satellite data for my home location. This was handled in a straightforward manner through the software's Map Library function on the NetLink tab. Purchasing (I have an annual subscription for data, so there was no immediate cost) and downloading the files took well under a half hour. I have a broadband connection, and the download itself took just moments. Uploading the files to the card (for color satellite images, these are large) took the most time and ate a lot of memory, in comparison to the coverage. The PN-40 will handle up to a 32 GB Secure SD card. If I needed extensive satellite imagery (which I do not; it is not navigationally useful in this region) I would probably need to buy one or more of these. As it is, between the map storage that's internal to the PN-40, and a 2 GB card, I have DeLome's detailed basemaps for most of my region on the unit, as well as a USGS maps for the entire Catskill mountain region, some satellite data, and room left over.

The PN-40 works very well as a substitute for a bicycle computer. It shows my maximum, actual, and average speeds, and offer all the advantages of a GPS's location-finding ability. I have a rack mounted to my handlebars which holds the unit safely in position.

The new firmware for the PN-40 upgrades its geocaching capability. I do not geocache, but I will report on how useful the PN-40 is for this popular pursuit in the Long Term report.

SUMMARY

The DeLorme PN-40 has so far been, disregarding a few minor quirks, an extremely powerful tool. With rare exceptions, the speed with which it calculates my position is exceptionally rapid, and appears highly accurate. The compass function (with its ability to show travelling direction on the fly on the main screen) is invaluable. In short, this is a very good GPS, well-supported by the manufacturer. My long-term test results will be available in late July.

LONG TERM REPORT

FIELD LOCATIONS AND CONDITIONS

I have used the PN-40 for one more backpack and numerous dayhikes in the Catskills and Shawangunks, as well as a brief geocaching adventure. This has been a wet summer, but I have been fortunate in picking dry, pleasant summer days for my trips. Daytime temperatures have been up to 80 F (27 C), and the nighttime temperature was around 45 F (7 C) on my one overnighter. The GPS was used both off and on trail, although always as a back-up source of navigational data.

PERFORMANCE IN THE FIELD

As promised in the field report, I experimented in the use of the unit for geocaching. I was able to quickly and accurately locate one cache. The other has remained elusive, but whether this is due to a lack of skill on my part, an error in the location given by the person locating it, or error in the PN-40, is impossible to establish. Quite likely, it is a combination of all three. On the first (successfully found) geocache I noted that there was a distance error of about twenty feet, but this didn't necessarily originate with the PN-40. My overall experience is that the PN-40 is quite accurate in most circumstances.

Geocaching is facilitated both by a special screen for controlling geocache lists (this permits comments etc., though I have not explored all aspects of this), and a browser add-on prepared by DeLorme that enable geocache waypoints to be directly downloaded to the unit from geocaching.com, one of the most popular websites devoted to this sport. Both Firefox and Internet Explorer versions are available. This is obviously a very handy feature for anyone into the sport. Unfortunately I am not an aficionado, and can merely comment that the software feature for browsers works, and that I had, for whatever reasons, mixed success in finding the caches.

Since the Field Report, a further firmware upgrade has been released (2.6 Official Release). Installing was smooth sailing. In addition, a new version of Topo USA version 8.0, was generously provided by DeLorme. This has some additional features, but nothing that strikes me as a radical alteration. I have found that the software works best if I reboot my machine after using the msconfig command in Windows XP's Run command line to turn off the firewall, virus checker etc. After cutting my maps etc., I simply reset the computer back to boot to normal, and reboot. It's a mild nuisance, but it seems something I run does not "play nice" with Topo.

The PN-40 unit has performed absolutely smoothly. I have been running it with a rechargeable Li-ion battery, which I don't ever remove. I just plug in a USB charger overnight to charge the unit up. I've not had any further issues with the unit having serious problems obtaining a positional fix, although I do sometimes help it after driving some distance by using a setting (under the satellite page) that enables me to "tell" the GPS where it now is, which accelerates signal capture. I haven't had any issues with communication between the PN-40 and my computer

The most exciting development I have found is one that uses optional software. I purchased a copy of DeLorme's XMap Professional, which is available to PN-40 users for just under $100 US. This is a program not unlike Topo in overall appearance and functionality. It enables me to take a scan of any map, and register it positionally, so it has an embedded coordinate system. The map can then be "cut" and loaded to the GPS. The result is that, in addition to the imagery supplied by DeLorme, I now have many of my favorite hiking maps loaded on the PN-40, and I can switch from (say) the USGS view of the terrain to the hiking map at will, by use of the map layering controls.

This is obviously very handy when bushwhacking towards a trail, for example; beyond that, it's an extremely nifty feature that adds a great deal to the PN-40's functionality. The only downsides are the added expense (I wish this was incorporated directly in Topo USA for the PN-40, since it adds so much utility); the difficulty in obtaining good scans of large maps with the typical small home scanner (but that's a test of ingenuity and Photoshop chops); and last (and not least) the fact that only two registration points are allowed. The full-scale version of XMap (an expensive product that apparently goes far beyond the "Professional" version) permits multiple registration points to be used to establish a coordinate framework, which I suspect would give better overall accuracy. Still, with a scanned map covering an area of about 50 square miles, all the major trails I have tested are within a hundred feet or so of where the GPS indicates, a testament to both the quality of the hiking map in question, and the DeLorme XMap package.

SUMMARY

The PN-40 GPS is well supported by the manufacturer, and offers capabilities that I have not seen on other GPS units. The screen is very clear and bright, and the controls easy to operate. DeLorme regularly updates the firmware, and seems intent on adding new features and improving existing ones. This has become my favorite GPS unit, and I expect to keep using it for the foreseeable future.

Many thanks to DeLorme and BackpackGearTest for the opportunity to test the PN-40 GPS. This report was created with the BackpackGearTest.org
Report Writer currently at version 1.5. Copyright 2008. All rights reserved.

Product tested and reviewed in each Formal Test Report has been provided free of charge by the manufacturer to BackpackGearTest.org. Upon completion of the Test Series the writer is permitted to keep the product. Owner Reviews are based on product owned by the reviewer personally unless otherwise noted.